Liquid cylinder system



July 16, 1968 R. c. WOERNER 3,392,537

LIQUID CYLINDER SYSTEM Filed March 29, 1967 2 Sheets-Sheet 2 FIG. 3. Ni12 I0 TO CUSTOMER so. 70 WK 9%; 30' \46 7* 30 J" 48 74 (I03 I02 -100 10!36 "1. 4 f I 36 105 C): I 0 g C) '6) (P (P INVENTOR RIC HARD C. WOERN ERSY ATTORNEY United States Patent Oflice 3,392,537 LIQUID CYLINDER SYSTEMRichard C. Woerner, Scotch Plains, N.J., assignor to Air ReductionCompany, Incorporated, New York, N.Y., a corporation of New York FiledMar. 29, 1967, Ser. No. 626,727 16 Claims. (CI. 62-50) ABSTRACT OF THEDISCLOSURE This invention is directed to a distribution system forvaporizable liquid in which the liquid is stored in individual storagecontainers and is dispensed under pressure. A pressurizing system isassociated with at least one of the storage containers to maintain adesired pressure in the system.

This invention relates to distribution systems for cryogenic gases. Moreparticularly the invention relates to the distribution of gas, in vaporphase, in a system having cylinders in which the gas is stored in liquidphase. The invention is intended primarily for bulk distribution ofgases, such as oxygen, nitrogen and/or argon, which can be moreconveniently stored as liquids in individual containers.

It is an object of this invention to provide an improved gasdistribution system, with a plurality of liquid storage cylindersconnected in series and pressurized to make the rate of withdrawal ofliquefied gas from the cylinders independent of the number of cylindersin the system.

Another object is to provide a gas distribution system with liquidstorage cylinders connected in series for sequential delivery of theliquid from successive cylinders and with means for pressurizing thesystem through pressure applied to the last cylinder in the series. Theinvention provides for replacement of empty cylinders with fullcylinders without interrupting the supply of gas to the customersdistribution line, and for changeover to other independent,series-connected, liquid storage cylinders as those of a first groupbecome exhausted.

Another object relates to an improved method of connecting the liquidstorage cylinders in different groups for efiicient operation andeconomy in the use of cylinders.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like referencecharacters indicate corresponding parts in all the views:

FIGURE 1 is a diagrammatic view of a cryogenic gas distribution systemmade in accordance with this invention;

FIGURE 2 is a diagrammatic view showing a subsequent arrangement ofcylinders for use in the distribution system shown in FIGURE 1; and

FIGURES 3 and 4 are diagrammatic views showing modified forms of thedistribution system shown in FIG- URE 1.

The gas distribution system shown in FIGURE 1 includes a customers linehaving a pressure gauge 12 and a line pressure regulator 14. Thiscustomers line 10 is connected with the downstream end of a vaporizer16; and liquid is supplied to the upstream end of the vaporizer 16through a liquid supply line 18. A gauge indicated the pressure in theliquid supply line 18.

The pressure gauges 12 and 20, pressure regulator 14 and vaporizer 16may be mounted in a control panel for the convenience of the operator.The vaporizer 16 preferably may comprise one or more passes of tubing onwhich are mounted heat absorbing fins. The purpose of the vaporizer is,of course, to warm up the cryogenic liquid 3,392,537 Patented July 16,1968 so that it changes from a liquid phase to a gaseous phase. In mostcases, the customers desire a gaseous product. Of course, this systemcan also deliver liquid product to a use point. This can be accomplishedby taking liquid directly from a cylinder and not sending it into thevapor- 1zer.

The liquefied gas for the liquid supply line 18 comes from a group ofstorage cylinders 24, 25 and 26 connected in series with one another. Adischarge pipe 28 leading from the lower end of the cylinder 26 isconnected with the liquid delivery line 18 by a connector 30. There is ashut-01f valve 34 in pipe 28 at the upper end of the cylinder 26. Thevalve 32 may be mounted on the abovementioned control panel.

Each of the cylinders in the First Group is provided with a longdischarge pipe 28 which extends through the top of the cylinder andterminates adjacent the bottom of the cylinder and a short pipe 47 whichalso extends through the top of the cylinder and terminates close to thetop of the cylinder.

As shown in FIG. 1 the long pipe 28 in cylinder 25 is connected to theshort pipe 47 in cylinder 26 by means of a flexible tubular connector36. The long pipe in cylinder 24 and the short pipe in cylinder 25 aresimilarly connected. Both the long and short pipes may 'be closed off bymeans of valves which are illustrated schematically in FIG. 1. Flexibletubular connectors are used due to the fact they are easy to handle andallow for some relative movement between the cylinders.

The cylinders 24, 25 and 26, which are in fact representative of all thecylinders in the different embodiments discussed below, are of thevacuum jacketed variety. Many different kinds of vacuum insulatedcylinders that are specifically designed for storing cryogenic liquidsare commercially available. A specific description of the structure ofthe cylinders is therefore unnecessary. The reference number 40 is usedto denote the vacuum space between the interior cylinder 40a and theoutside cylinder 40b.

The flexible tubular connectors 36 are not vacuum insulated andtherefore ambient temperature comes in relatively close contact withproduct passing through the connector. The purpose this serves will bedescribed below.

For purposes of explanation, cylinder 26 will be referred to as thefirst cylinder and cylinder 24 as the last cylinder in the first group.A liquid line 42 is connected with the bottom of the last cylinder 24and conducts liquid to to a vaporizer 44 which is located in the bottomportion of the vacuum space 40b in the last cylinder. The vaporizer mayconveniently be a single turn of tubing wrapped around the lower end ofcylinder 40a and is shown schematically in FIG. 1. The vaporizer couldbe located outside the cylinder 24, but this is not preferred since itwould be more susceptible to damage.

For purposes of standardization, each cylinder, in the preferredconstruction, is equipped with an internal vaporizer 44 which can bereferred to as an internal pressure building coil. This coil would beconnected to a valve 34, on the upper portion of the cylinder so thatflow through the coil can be controlled. When the cylinders areconnected in series as in FIG. 1, only the vaporizer or pressurebuilding coil in the last cylinder in the series is operated. Thepressure building coils in the remaining cylinders are closed off bymeans of the aforementioned valves.

The downstream end of the vaporizer 44 associated with the last cylinderis connected by a tubular line to a valve 56a in conduit 46. The valvemay be mounted on the aforementioned control panel. Conduit 46 extendsinto the control panel and then back to the cylinder 24 and is connectedto pipe 47. A shut-off valve 34 is positioned in said connection. Apressure building regulator 48 is positioned in line 46 and is set tomaintain a desired pressure in cylinder 24. This is accomplished in thefollowing manner. When valves 34, 56a and 58b are opened and valves 46band 58a are closed and the pressure in cylinder 24 is less than thatdesired as determined by the set pressure on regulator 48, the regulator48 will open. Liquid which is in the coil 44 will vaporize and passthrough conduit 46, regulator 48 and back into the upper portion ofcylinder 24. Vaporization takes place in coil 44 due to the fact thatthe temperature in the space 40 is higher than in the cylinder 40a. Thisvaporization and consequent pressure build-up will continue until thepressure in cylinder 24 and in conduit 46 reaches the set pressurebuildup regulator. At that time, regulator 48 will close and prevent theremoval of further liquid from the bottom of the cylinder 24. Theregulator 48 will remain closed until the pressure in the cylinder 24drops below set pressure at which time it will open and allow flowthrough conduit 46. The specific structure of the pressure buildupregulator will not be described in view of the fact that many differentvarieties of pressure regulators are known in the art and could be used.In a typical pressure buildup regulator the pressure downstream of theregulator is continually sensed, as for example through conduit 48a.This sensed pressure could, for example, act against a preset springforce to regulate downstream pressure.

The delivery pressure of the regulator 48 is the pressure in the entiregroup of cylinders 24, 25 and 26, since these cylinders are directlyconnected in series with one another; and it is also the pressure atwhich liquid is supplied from this first group of cylinders to theliquid delivery line 18 and to the upstream end of the vaporizer 16.Thus the pressure indicated by the gauge is substantially the samepressure as the delivery pressure of the regulator 48 with some drop forthe losses incident to the flow of the liquefied gas through thedifferent passages and fittings.

When liquefied gas is supplied to the vaporizer 16 from the first groupof cylinders, the cylinder 26 has its liquid drawn off first. The liquidin the tubing connection 36 between the cylinders and 26 is subject tosome evaporation as a result of heat absorbed from the ambientatmosphere and the vapor produced by this evaporation is enough tomaintain the gas pressure over the liquid in the cylinder 26 as thelevel of liquid is drawn down with discharge of liouid through the pipe28 and the liquid delivery line 18 to the vaporizer 16.

As soon as the liquid in the cylinder 26 has dropped below the lower endof the pipe 28, the vapor pressure in the cylinder 26 begins to dropfaster than the rate of evaporation in the tubing connection 36 andliquid from the cylinder 26 is forced out through the pipe 28 ofcylinder 25 into the cylinder 26 for further discharge into the liquiddelivery line 18. With liquid flowing in the tubing connection 36, itonly remains long enough to be partly vaporized by heat leakage.

It has been found that as cylinder 26 empties of liquid, approximately 4or 5% of the contents of cylinder 25 is removed in order to maintain aconstant pressure in cylinder 26. After the cylinder 26 has been emptiedto the level of the lower end of tube 28 there is intermittent liquidand gas flow from cylinder 25 to cylinder 26 in order to maintain theliquid level just at the tube 28 entrance opening. Cylinder 25 continuesto supply its liquid to cylinder 26 until its liquid level drops to thelevel of the entrance to tube 28. While this liquid level has beendropping, cylinder 24 has been providing a small amount of liquid to bevaporized in connecting line 36 so as to maintain the pressure incylinder 25 in much the same manner that cylinder 25 provided a smallamount of liquid to maintain pressure in cylinder 26. Similarly when theliquid level in cylinder 25 drops below the tube entrance 28, anintermittent flow of liquid and vapor will flow from cylinder 24 so asto maintain the liquid level at the entrance to the tubes 28 in bothcylinders 25 and 26.

In order to further stabilize the system ithas been found helpful toplace restrictor plugs in the connecting lines 36. These plugs, whichcontain orifices serve to further control the fluid flow into the nextupstream cylinder.

It has been noted that when liquid is being transferred from cylinder 24to cylinder 25, the tubing connection 36 becomes completely frosted.This would indicate to an alert operator that he is operating on hislast cylinder and replacement cylinders should be ordered. The method bywhich the operator incorporates new full cylinders in the system will bediscussed below.

It has been found that under certain conditions pressure builds up inconduit 46 and in the cylinder 24, This pressure buildup can exceed theset pressure of regulator 48 since this valve only operates to open whena pressure lower than the set pressure is sensed. To relieve thispressure build up an economizer regulator 70 is provided in a conduit 68which connects the conduits 46 and 18. The economizer regulator is setat a pressure higher than the regulator 48 and will lift when thispressure is reached and dump the pressurized vapor into the vaporizer16.

The excess pressure buildup in the system could be caused by a number ofthings. For example heat leak due to close proximity to a heat sourcesuch as a radiator, engine etc. Heat leak over a prolonged period duringwhich the system is not in operation.

In a typical operational set up regulator 48 will be set at p.s.i.regulator 70 at p.s.i. and regulator 14 at 75 p.s.i. It has been foundthat a 25 lb./in. increment between regulators 48 and 14 provides goodoperating characteristics.

When cylinders 25 and 26 are essentially evacuated and cylinder 24 isfurnishing the liquid to be veporized in the vaporizer 16, the operatorshould replace the evacuated cylinders with full ones. There are anumber of ways in which this can be done, one of which is illustrated inFIG. 1. The system is designed so that gas flow to the consumer line isnever interrupted.

Each pipe 28 is provided with two connections, controlled by valvesthrough which liquid can be drawn. On seeing that cylinder 24 issupplying liquid, the operator connects a conduit 1811 between thesecond connection on tube 28 on cylinder 24 and connector 30' ondelivery line 18. Thus the connection between cylinders 24 and 25through conduit 36 may be maintained while the connection to line 18 ishooked up. When the last mentioned connection is complete and theassociated valve set 34 opened, valve 32 in the line 18 may be closedand valve 32' opened simultaneously. These valves may be convenientlylocated on the control panel. Thus liquid will be continuously suppliedto vaporizer 16. When this is done the valve 34 associated withconnection 36 between cylinders 24 and 25 should be closed. Theconnections between cylinder 26 and line 18, and between cylinders 24,25 and 26 may then be broken and cylinders 25 and 26 removed. Onlycylinder 24 will then be operating to supply liquid product. Replacementcylinders 52 and 51 are then connected in series relationship withcylinder 24 in the manner shown in FIG. 1, second group. The pressurebuilding circuit associated with the last cylinder 51 in the group isthen connected to valve connections 56b, 58a and pressure is built up incylinders 51 and 52 until they are at the same pressure as cylinder 24.When this has been done the valve 34 in pipe 47 of cylinder 24 is openedand the pressure building circuit associated with cylinder 24 is closedoff and disconnected. Thus the last cylinder 51 will pressurize thepreceding cylinders in the manner described above in connection withcylinder 24 in the first group. The pipe 47 in cylinder 24 has a dualconnection so that a concurrent coupling with both the line 46 and theassociated interconnecting conduit 36 to cylinder 52 may be had.

When cylinders 24 and 52 have delivered all their fluid and cylinder 51is supplying the demand, the operator proceeds to replace the emptycylinders with new ones 64, 65 in the same manner as described abovewith reference to cylinders 25 and 26. The operational set-up in whichcylinders 64 and 65 are on the line is shown in FIG. 2.

In another and more simple embodiment of the invention the independentvalves 56g, 56b and 58a, 58b can be replaced by a pair of three positionselector valves so that by merely turning a single valve alternatesupplies could be selected. The third position of the valve wouldinterrupt flow entirely.

In the simplest embodiment the valves 56a, 56b, 58a, and 58b areentirely eliminated. This embodiment is shown in FIG. 3 in schematic.The vaporizer 44 is connected to line 46 by means of a conduit 100 and aconnector 102. Similarly the tube 47 is connected to the line 46 byconduit 101 and connector 103. The connectors may be of the conventionalscrew variety used in cryogenic couplings. When operating on the liquidsupply of the last cylinder '24 as indicated by excessive frosting inthe line 36 between cylinders 24 and 25, a connection 105 is madebetween the discharge tube 28 of cylinder 24 and delivery line 18through connection 30' as shown in dotted lines. As mentionedpreviously, tube 28 has two outlet connections each controlled by avalve 34. When this connection is complete the valve 32' is opened andvalve 32 is closed so that liquid from cylinder 24 goes directly to line18'. Cylinders 25 and 26 are then disconnected and replaced with fullcylinders 52 and 51. After the series connection between cylinders 24,52 and 51 are made, as shown in FIG. 1, second group, the pressurebuildup circuit of cylinder 24 is disconnected at the cylinder. The sameconnecting lines 100 and 101 can then be used to connect up the pressurebuilding circuit in the last cylinder 51 in the series. It has beendiscovered that the pressure from the cylinder 24 will not dropsignificantly over the short period of time it takes to hook up thepressure building circuit to the last cylinder in the series. This lastmentioned simplified embodiment is much less expensive in that thevalves 56a, b and 58a, b are eliminated.

The system is provided with valves and connectors wherever needed and isalso provided with safety valves 74 at all locations where pressure maybuild up when the passages beyond these locations are shut off by closedvalves or where the system is improperly operated.

FIG. 4 shows a modified form of the invention. The distribution system,except for the cylinders, is essentially the same as in FIG. 1 thoughthe positions of various parts are not the same. However, thecorresponding parts are indicated by the same reference characters as inFIG.

1 and with a letter a appended. The system is somewhat simplified inthat safety valves and connections are omitted, but it will beunderstood that this is merely to simplify the drawing and that inactual practice these safety valves and connections are provided whereneeded as in FIG. 1.

The cylinders shown in FIG. 4 are the same as those used in theembodiments shown in FIGS. 1, 2 and 3. The pressure building coils 86are shown in each cylinder 81, 82, 83, 84 for purposes of illustration.Conduits 88 extend down through the vacuum space to the coils. In FIG. 4the coil 86 of the cylinder 81 is used to pressurize the cylinders inthe first group in the same manner that coil 44 in cylinder 24pressurizes the cylinders of the first group in FIG. 1. In thisarrangement the groups are arranged so that they can supply thevaporizer 16a alternately. When the first group is supplying liquid andvalve 91 is open and 92 closed, back pressure regulator 48a serves tomaintain pressure in the cylinders on the left and conduit 18a directsliquid from said cylinders to the vaporizer. Economizer regulator 70adirects fluid to the vaporizer through a check valve in line 46a whenits set pressure is exceeded. The regulators 48a and 70a work in thesame manner as regulators 48 and 70, described above. When the liquid inthe first group is almost exhausted, control valve 91 is closed andcontrol valve 92 is opened. By doing this the flow of liquid from thefirst group of cylinders will be interrupted and the flow from thesecond group will be connected. Check valves 93 and 94 prevent theback-up fluid in lines 46a. By arranging the cylinders as described inFIG. 4, a continuous supply of fluid to the vaporizer 16a is assured.With valve 91 closed, empty cylinders in the first group may bereplaced.

It will be understood that the groups of cylinders in FIG. 3 can containmore than two cylinders, just as the groups shown in FIG. 1 can containmore than three cylinders, if desired. In practice, the number ofcylinders used in each group depends upon the gas requirements of thecustomer. If a customer requires large amounts of gas, more cylindersare used so as to reduce the frequency of visits which the gas supplierhas to make to the customers plant.

The preferred embodiment of the invention has been illustrated anddescribed, but changes and modifications can be made and some featurescan be used in different combinations without departing from theinvention as defined in the claims.

What is claimed is:

1. A cryogenic liquefied gas distribution system including a pluralityof storage cylinders for gas in liquid phase and under pressure, tubingconnections from the lower part of one cylinder to the upper part of thenext cylinder, said tubing connections connecting the cylinders inseries with one another, a vaporizer from which gas is supplied to acustomers line, a liquid-conveying line from the first cylinder in theseries to the vaporizer, means for maintaining a pressure on the liquidin the series-connected cylinders including apparatus that vaporizesliquid of the last cylinder in the series, a gas line through whichvaporized gas from the last cylinder is delivered back to said lastcylinder to increase the pressure of gas above the liquid in the lastcylinder and to maintain pressure on all of the series-connectedcylinders.

2. The distribution system described in claim 1 characterized by themeans for maintaining pressure on the liquid in the last cylinderincluding a pressure building vaporizer, a liquid supply line leadingfrom the lower part of the last cylinder to one side of the pressurebuilding vaporizer, a gas line leading from the other side of thepressure building vaporizer to the upper part of the last cylinder, anda pressure-maintaining regulator in said gas line for regulating thepressure of the gas.

3. The distribution system described in claim 1 characterized by thestorage cylinders being at least partly vacuum-jacketed and the tubingconnections from each cylinder to the next cylinder including a portionthat extends outside of the jacket and in which some liquid is vaporizedby heat leakage from the ambient atmosphere through said tubingconnections when the cylinder to which a tubing connection suppliesliquid is partially full and there is little or no flow from the nextcylinder to the partially full cylinder.

4. The distribution system described in claim 2 characterized by a linepressure regulator beyond the firstmentioned vaporizer and through'which gas from said vaporizer is supplied to the customers line, andthe pressure-maintaining regulator has a substantially higher deliverypressure from that of the line regulator.

5. The distribution system described in claim 2 characterized by aconnecting gas passage leading from said gas line to the firstvaporizer, and an economizer regulator in said connecting gas passageand having a delivery outlet communicating with the first vaporizer, theeconomizer regulator having a delivery pressure substantially higherthan that or the pressure regulator in said gas line from the pressurebuilding vaporizer to the last cylinder.

6. The distribution system described in claim 4 characterized by aneconomizer pressure regulator communicating at its upstream side withsaid gas line at a location on the downstream side of thepressure-maintaining regulator, and said economizer pressure regulator,pressuremaintaining regulator and line regulator having progressivelylower delivery pressures differing from one another by substantialamounts.

7. The distribution system described in claim 6 characterized by thedelivery pressure of the economizer pressure regulator,pressure-maintaining regulator and line regulator being 150; 100 and 75pounds per square inch.

8. The distribution system described in claim 1 characterized by twodifferent liquid delivery lines leading to the vaporizer, withconnections for connecting each liquid delivery line with a differentgroup of series-connected cylinders, and valve means in the liquiddelivery lines for shutting off one line from the vaporizer for changeof cylinders in the group that is connected with that line.

9. The distribution system described in claim 2 characterized by the gasline having branches at one end for alternately connecting with anotherpressure building vaporizer on a different group of liquid storagecylinders, and having branches at the other end for alternatelyconnecting with the last cylinder of different groups of cylinders, andvalve means for selectively shutting off either of the branches of saidgas line.

10. The distribution system described in claim 2 characterized by eachof the cylinders having a liquid storage compartment and a vaporizercoil extending around the liquid storage compartment, valve means at thedelivery end of each coil, the vaporizer coil of the last cylinder beingthe pressure building vaporizer, and the vaporizer coils of the othercylinders being available for use as pressure building vaporizers whenand if the cylinder positions are interchanged.

11. The distribution system described in claim 2 characterized by asecond group of cylinders including a last cylinder with a pressurebuilding vaporizer, the pressure building Vaporizers being located belowthe level of the liquid in the last cylinders of their respectivegroups, different branch lines connecting the pressure buildingvaporizers with the same gas line on the upstream side of thepressure-maintaining regulator, different branch lines connecting theupper portions of the last cylinder of each of the different groups withthe gas line on the downstream side of the pressure-maintainingregulator, switchover means for the different branch lines forselectively putting the last cylinder of either group into communicationwith the pressure-maintaining regulator, other valve means between thepreceding and last cylinders of each group for isolating the lastcylinder to permit removal of the last cylinder from each group,connections for putting the last cylinder of one group into the secondgroup as the first cylinder of the second group, a liquid delivery lineleading from the first cylinder of the second group to the firstvaporizer, valve means in each of the liquid delivery lines forselectively shutting off each of the cylinder groups from the firstvaporizer, and a connecting gas passage leading from the gas line on thedownstream side of the pressure-maintaining regulator to the upstreamside of the first vaporizer, and an economizer pressure regulator insaid connecting gas passage, the economizer pressure regulator having adelivery pressure substantially higher than that of thepressure-maintaining regulator.

12. The method of supplying cryogenic gas from seriesconnected storagecylinders to a customers supply line, which method includes storing thegas in liquid phase in said cylinders, withdrawing liquid from thebottom of the first cylinder, vaporizing the liquefied gas withdrawnfrom the first cylinder, regulating the pressure of the vaporizedliquid, and supplying the gas in vapor phase to the customers line at aregulated pressure, supplying liquefied gas from the bottom of onecylinder to the top of the next preceding cylinder, withdrawingliquefied gas from the last cylinder, vaporizing the liquefied gas fromthe last cylinder, and regulating the pressure of the vaporized gas fromthe last cylinder and returning that gas to the top of the last cylinderto pressurize the liquefied gas in the series-connected cylinders.

13. The method described in claim 12 characterized by drawing downsuccessive cylinders in sequence, vaporizing liquefied gas inconnections between successive cylinders during the time in which theliquid level is being drawn down in the next preceding cylinder beyondthe connection to supply gas to the space in said next cylinder abovethe falling liquid level therein and at a pressure to maintain thepressure in the cylinder in which the liquid level is being drawn down.

14. The method described in claim 12 characterized by supplying gasdirectly from the last cylinder to the customers supply line in vaporphase whenever the pressure in the last cylinder exceeds a set pressure.

15. The method described in claim 12 characterized by supplying gasalternately from two different groups of storage cylinders with thecylinders of each group connected in series for successive drawing downof the liquid in the cylinders starting with the first cylinder of oneof the groups and before drawing down completely the liquefied gas inthe last cylinder of the said one group, shifting from supplying gasfrom said one group to another group so that the gas supply isuninterrupted.

16. The method described in claim 12 characterized by withdrawing liquidfrom said series until the liquid is entirely supplied from the lastcylinder, removing liquid from the bottom of said last cylinder andvaporizing it, replacing the empty cylinders in the series With fullones, discontinuing the pressurization of the said last cylinder andcommencing the pressurization of the last of the series of replacementcylinders.

References Cited UNITED STATES PATENTS 2,968,162 1/1961 Acomb 62503,066,495 12/1962 Biggins et al. 6250 3,319,432 5/1967 Nebgen 62453,319,433 5/1967 Pauliukonis et a1. 6245 LLOYD L. KING, PrimaryExaminer.

